Apparatus for pulling-off the skin of sheep carcasses in slaughtering

ABSTRACT

An apparatus for pulling-off the skin of sheep carcasses in connection with slaughtering comprises an essentially horizontal drum (8) for pulling-off the skin during winding thereof on the drum (8), the drum (8) being moved upwards along the dorsal side of a sheep carcass (31) suspended from the hind legs. The drum (8) has a gradually increasing diameter from a central portion towards both ends, and is mounted at the free end of a pivotable lifting beam (3) having a means (I) for upwards directed pivoting movement of the beam during the pulling operation. A motor means provides for rotation of the drum (8) synchronously with the pivoting movement of the lifting beam (3) and with a speed which is adapted to the movement of the lifting beam.

The present invention relates to an apparatus for pulling-off the skinof sheep carcasses in connection with slaughtering, comprising anessentially horizontal drum which is arranged to pull off the skinduring winding thereof on the drum, the drum being moved upwards alongthe dorsal side of a sheep carcass suspended from the hind legs.

In connection with slaughtering of big cattle there are known devicesfor hide pulling wherein a drum is arranged to pull off the hide duringsimultaneous winding thereof on the drum. However, the known devices arenot practically usable for pulling-off of skins in sheep slaughtering,as they do not provide for the necessary and appropriate distribution ofthe pressure on the skin and the sheep carcass around the whole carcass,with the result that the carcass cracks on exposed places, and themembrane which is to remain on the carcass is pulled off together withthe skin.

The object of the invention is to provide an apparatus for pulling-offskins of sheep and lamb carcasses by which there is achieved a rationaland effective skin pulling, and wherein the drum is especially shaped inorder to achieve reduced working effort in flaying and simultaneouslyensure gentle skin pulling without damage of the carcass.

The above-mentioned object is achieved with an apparatus of the type setforth above, which, according to the invention, is characterized in thatthe drum has a gradually increasing diameter from a central portiontowards both ends, and is mounted at the free end of a pivotable liftingbeam which is provided with a means for upwards directed pivotingmovement of the beam during the pulling operation, and that there isprovided a means for rotation of the drum synchronously with thepivoting movement of the lifting beam and with a speed which is adaptedto the movement of the lifting beam.

The invention will be more closely described below in connection with anexemplary embodiment with reference to the accompanying drawings,wherein

FIG. 1 shows a side view of a schematically shown skin puller apparatusaccording to the invention;

FIG. 2 shows a front view along the line II--II in FIG. 1;

FIG. 3 shows a top view of the apparatus in FIG. 1; and

FIG. 4 and 5 schematically illustrate two different operational phasesduring a skin pulling-off operation.

As shown in FIGS. 1-3, the skin puller apparatus in the illustratedembodiment comprises a vertically disposed, rectangular steel frame 1having vertical side members carrying suitable bearing means 2 forpivotal mounting of one end of a lifting beam means 3. The bearing means2 may be displaceably mounted on the side members of the frame. Thelifting beam means 3 comprises a pair of e.g. telescopically extendabletube and rod members 4 and 5 and a pair of bracing members 6 extendingtherebetween. On the free ends of the rod members 5 there are mountedbearings 7 for the support of an essentially horizontal drum 8 which isto be described below. The lifting beam means with the drum is pivotableupwards and downwards by means of an operating means which in theillustrated embodiment comprises a hydraulic cylinder and piston unit 9(cylinder I). At its upper end the hydraulic cylinder 9 is pivotallyconnected to an upper cross member of the frame 1, whereas the lowerfree end of the piston rod 10 is pivotally mounted between a pair ofholding plates 11 attached on the bracing members 6 and provided with aplurality of apertures 12 or the like for adjustable mounting of thepiston rod end.

On the subgrade, at a suitable distance in front of the lifting beammeans 3, there is provided a clamping means with a combined holding andstretching funtion which is to be described more closely below inconnection with the use of the apparatus. In the illustrated embodimentthe clamping means comprises a supporting frame 13 for the support of ahydraulic cylinder/piston unit 14 (cylinder II). At its lower end thehydraulic cylinder is pivotally connected to the supporting frame 13,and by means of a supporting means 15 the cylinder is supported in anoblique position as shown in FIG. 1. On the upper end of the piston rod16 of the cylinder/piston unit 14 there is mounted a gripping head means17 with gripping jaws 18 which are operable by means of a hydrauliccylinder/piston unit 19 (cylinder III).

In the shown embodiment the drum 8 comprises a central cylindricalportion 20 which at each end merges into a portion 21 having a graduallyincreasing diameter in the direction towards the ends of the drum, ande.g. having a conical shape. On each drum end there is provided anessentially circular end plate 22 having a larger diameter than that ofthe outer ends of the drum 8 and being provided with a hook portion 23which in the illustrated example is formed by an essentiallytangentially extending notch in the end plate in question. Theimportance of the concave or saddle-like drum shape is to be describedmore closely below in connection with the operation of the apparatus.

For rotation of the drum 8 a motor 24, which e.g. may be of hydraulictype, is provided at the free end of one of the lifting beam rod members5. The motor is supported by a bracket means 25 attached to the rodmember 5, and is connected to the shaft of the drum 8 through a suitableclutch 26.

For the operation of the described operating and driving means which areincluded in the shown embodiment of the apparatus according to theinvention, there is provided a hydraulic unit 27 which, at the base ofthe vertical steel frame 1, is supported by a base plate 28 which is inturn supported on a frame 29 through buffers 30.

The various hydraulic and/or electric supply conduits, and the variousconnections and control means, such as control valves and the like,which are necessary for operation and control of the apparatus, are notillustrated in the schematic drawing figures. The arrangement of thesemeans is of technical kind and therefore is not more closely shown anddescribed, as a person skilled in the art will realize the necessaryarrangement in view of the following description of the operation of theapparatus. Similarly, it will be seen that the apparatus may possibly beadapted for pneumatic instead of hydraulic operation.

In the following a skin pulling-off operation will be described withreference to FIGS. 4 and 5.

When a sheep carcass arrives at the skin puller apparatus, it has beenflayed from the breast and just beyond the navel. The skin is cut fromknee joint to knee joint at the front edge of the breast. The forelegshave been cut off at the knee joint, but the metatarsal bones stick tothe skin.

The initial or zero position of the apparatus is shown in FIG. 4. Thesheep or lamb carcass 31 is suspended from the hind legs in connectionwith a suggested overhead conveyor 32. Further, the sheep carcass isclamped in that the ends of the "antibrachial bones" (i.e. the forelegsabove the knee joint) are introduced into and clamped between thegripping jaws 18 of the clamping means, the cylinder III being activatedfor this purpose. As mentioned, the metatarsal bones 33 stick to theskin and are introduced in the notches of the drum end plates 22 andthus secured by means of the hooks 23 at each end of the drum.

The drum and the lifting beam now start automatically and synchronously,and the drive motor 24 rotates the drum 8 in the direction of the arrowA in FIG. 4 at the same time as the cylinder I gets instruction forupwards directed stroke movement with a set, reduced speed, so that oneachieves the correct angle for the pulling-off of the skin across theshoulder portion of the carcass, the skin now being wound onto the drum(in FIGS. 4 and 5 the inner side of the skin is marked with a hatchedarea). As shown in FIG. 4, the movement of the lifting beam 3 is startedfrom a somewhat lowered position in relation to the horizontal, and thesynchronized movement of the lifting beam and the drum is adjusted sothat one achieves the particular and intended pulling angle resulting inoptimum skin pulling.

When the drum has been raised a suitable distance (normally about 20cm), cylinder I gets instruction or order to continue its stroke, butnow with full speed, at the same time as cylinder II gets order forstroke, i.e. downward movement of the piston rod 16 with the clampingmeans. The antibrachial bones and therewith the sheep carcass arethereby stretched obliquely downwards and outwards from the lifting beamand the drum, such as it appears from FIG. 5 (the carcass is normallypulled somewhat more outwards from the drum than shown in the Figure).Thus, the skin is pulled off from the back at an angle of ca. 25°-30°.

The special configuration of the drum results in that the pressure onthe skin and the sides and back of the carcass is equalized anddistributed around the carcass itself, so that it does not crack. Theflank and the rearward part of the back (marked with x in FIG. 4) arecritical points in the use of a skin puller, and without the specialshape of the drum, the flank would crack and the membrane on the legwould be pulled off together with the skin.

By use of e.g. a straight drum it would be necessary with substantiallymore preparatory work during the slaughtering as the flank and the sideswould then have to be flayed by hand. With the present skin puller,however, the sheep carcass is flayed approximately 10 cm on each sidefrom the breast and just beyond the navel, so that the preparatory workmay be made much simpler. There will be less flaying, so that thesecond-class percentage of the skins becomes smaller. Less flayingfurther involves that the slaughtering may be carried out morehygienically and less laboriously.

When the lifting beam is at the top and the skin has been pulled off thecarcass, the metatarsal bones are cut off from the skin by means of apair of knives (not shown) arranged in connection with the overheadconveyor. Thereafter the lifting beam returns to its initial position atthe same time as the drum is rotated in the direction opposite to thewinding direction, so that the skin falls down from the drum and theapparatus thus is ready for another working cycle.

Instead of the shown clamping means with gripping head means withhydraulically operated gripping jaws, the clamping means may simplyconsist of a suitable hook means onto which the forelegs of the sheepcarcass may be hooked. A number of such hook means may be provided atdifferent heights along a rod which is pivotally mounted and fixable ina desired position on a supporting frame, so that one achieves adaptionfor clamping of carcasses of different sizes, and simultaneously, bypivoting of the rod, may pull the carcass outwards from the drum to themost suitable position for pulling-off of the skin.

I claim:
 1. An apparatus for pulling-off the skin of sheep, lamb orsimilar carcasses in connection with slaughtering, comprising anessentially horizontal drum which is arranged to pull off the skinduring winding thereof on the drum, the drum being moved along thedorsal side of a vertically suspended carcass characterized in that thedrum (8) has a gradually increasing diameter from the central portion(20) towards both ends and a clamping means to affix the skin to thedrum at the beginning of the cycle, said drum being mounted at the freeend of a pivotable beam (3) which is provided with a means (9) forpivoting movement of the beam during the pulling-off operation, alongand in engagement with the dorsal side of said carcass and that there isprovided a means (24) for rotation of the drum (8), said drum (8) beingrotated synchronously with the pivoting movement of the beam (3) andwith a speed which is adapted to the pivoting movement of the beamtraversing said dorsal side of said carcass whereby varying amounts offorce at varying angles are exerted on the skin responsive to the locusof the drum along the carcass, to most effectively and uniformly carryout the skin removal process with minimal damage to the skin.
 2. Anapparatus according to claim 1 characterized in that the carcass issuspended from the hind legs, and the apparatus comprises means (17-19)for clamping of the forelegs of a carcass (31), and which is arranged tostretch the forelegs, obliquely away from the beam (3) and the drum (8)after the beam (3) has been moved a predetermined distance.
 3. Anapparatus according to claim 2, characterized in that the drum is movedupwards during the skin pulling and the means (9) for pivoting movementof the beam (3) is arranged to lift the beam from an initial positionwith a first lower speed, which is adapted to the rotational speed ofthe drum (8), and thereafter with a higher speed.
 4. An apparatusaccording to claim 1, characterized in that the drum (8) comprisesessentially circular end plates (22) having a substantially largerdiameter than the end portions (21) of the drum, and being provided withrespective hook means (23) at corresponding places at the periphery ofthe end plates (22).
 5. An apparatus according to claim 1 or 2 or 4,characterized in that the movement means comprises a hydrauliccylinder/piston unit (9).
 6. An apparatus according to claim 2,characterized in that the clamping means (17-19) is mounted on the upperend of a piston rod (16) forming part of a hydraulic cylinder/pistonunit (14).
 7. An apparatus according to claim 2, characterized in thatthe clamping means (17-19) comprises gripping jaw elements (18) arrangedto be actuated by a hydraulic cylinder/piston unit (19).
 8. An apparatusaccording to claim 2, characterized in that the drum (8) is driven by amotor (24) which is arranged to rotate the drum (8) back to its initialposition during a return movement of the beam (3) to the initialposition thereof.